About 6,000 drug offenders will be released from federal custody over the next few days, but some legal experts warn that the government has done too little to help many of them successfully reintegrate into society.

The prisoners will be released from federal Bureau of Prisons custody on Friday and Monday as a result of a U.S. Sentencing Commission decision last year to cut sentences of drug offenders by an average of two years.

The vast majority have spent only a short time in a halfway house -- not the six months to a year normally required for drug offenses -- before being transferred to the much looser restrictions of home confinement.

Of the prisoners being released, 1,764 are not U.S. citizens. They will be turned over to Immigration and Customs Enforcement, and most of them will be deported.

Nearly 80% of the rest -- or about 3,400 -- already have moved to the Bureau of Prisons' halfway houses or were confined at home, but will be released from custody by Tuesday, according to the Justice Department.

The remaining 850 or so will be released directly from prison to a probation officer.

Prisoners being released include 250 from California, 310 from Florida, 260 from Illinois, 95 from Maryland, 100 from Pennsylvania, 163 from Virginia and 35 from Connecticut.

The decision not to require the prisoners to spend lengthy transition periods in halfway houses "is a major concern," said Malcolm C. Young, a Washington lawyer who works as a consultant on criminal justice issues.

“We have known for years that reintegrating people back into society is a challenge, and the results have not been very good,” he said.

The problem is overcrowding. About 6,000 federal prisoners are normally released under supervision each month, and many already fill the system’s 209 halfway houses.

“Halfway houses are pretty close to capacity,” said Young, who has been studying the issue but said he has been unable to get details from federal officials.

According to a study of halfway houses in Ohio between 2002 and 2007, 36% of prisoners who were released after leaving a halfway house were rearrested, compared with 49% of prisoners who were released without any formal transition.

Edmund Ross, a spokesman for the Bureau of Prisons, said that under normal circumstances, most prisoners are sent to halfway houses before transitioning to home confinement. If an inmate has a stable family situation, the halfway house stay can be as little as a day, he said.

“We’ve been able to utilize the halfway houses optimally,” he said, by moving people quickly into home confinement.

That won't happen to most of the prisoners being released in the coming days, however.

A senior Justice Department official, who spoke on condition of anonymity, said the Bureau of Prisons has prepared for the mass release for more than a year and has scheduled other releases to put “as many as possible” into halfway houses before this weekend.

The Sentencing Commission, an independent agency of the judiciary, voted last year to cut drug sentences by an average of two years. It followed up with a vote to make the reductions retroactive.